562 EHRENBERG ON THE ORIGIN OF ORGANIC MATTER 
substances, or its gradual formation, without however having noticed 
their complex internal structure ; whilst at the same time, I myself, who 
for a series of years had acquired a progressively deeper insight into 
the organization of these minute forms, which were said to be developed, 
destitute of organs, or imperfect, could never get a sight of their spon- 
taneous or gradual origin from molecules, slime, vegetable tissue, &c. 
A comparison of my observations on the bell-animalcule ( Vorticella 
Convallaria and other species of this genus), which had been made 
under geographical circumstances the most various, greatly confirmed 
my impressions; and the repetition, with redoubled care, of my inves- 
tigations of their gradual individual change, removed all doubts in 
regard to a whole series of beings of various kinds, in which I disco- 
vered a determinate cyclus of forms, deriving their origin from one 
another. These data, of which I became convinced, in beings so 
minute and so simple in appearance, incited me to direct my observa- 
tions, with increasing care, to this point, and gave me a certain 
anticipation of much more interesting results near at hand. High 
organization, and cyclical development of the molecules, were to me 
clear truths, floating in my imagination, and capable of more substan- 
tial proofs: my only search was for the means to produce them. 
Fortunate was the thought which brought to my recollection the 
coloured nutritive substances, already often tried by me without suc- 
cess. Confident of the result, I put various colouring substances into 
the water containing the infusoria, and awaited their reception into 
their organs of nutrition. The first experiments with common water- 
colours failed, although I had selected many different colouring matters; 
my conviction however of a better result was so strong, that Ino longer 
attributed its want of success to the organization of the animalcules, 
but to unsuitable colouring matters. Other experiments also proved 
unsuccessful. One day however I remarked, in experimenting, a 
whitish sediment at the bottom of the small glass plate on which I had 
mixed water colours with the water containing the infusoria; and as 
in general the colours of the shops are mixed with white lead, I made 
choice of some pure colours, and such as I supposed to be least 
disagreeing with animal organization; such I considered indigo, car- 
mine, and sap-green, as they are all of purely organic origin. With 
these I began my experiments anew, and here also the clew was found; 
all infusoria, even the smallest, soon filled themselves with the colouring 
matter. The opacity of the water caused by the colour, enabled me 
to distinguish much more clearly than the opacity caused by mud, 
which I had made use of in my former experiments on the cilia, not 
only the presence of the cilia, but also any separate part of the body 
to which the vortex caused by the cilia carried the nutritive particles, 
and where they were received into the interior of the body. 
From the transparency of all these animalcules, I could see very 
